Fitting headers in that truck could be a problem. The transmission crossmember is usually where most long tube headers would run. There was one company that made a run of long tube headers for Poly Sweptline trucks. I don't know if they are still available but Stan's might have them.
There were 2 other companies that made long tube headers for 67-68 trucks with the LA and big block. One was Hedman and I don't remember the other one.
1970 Dodge d100/eventually going on a 77 D100 frame
